Lock.



M. H. FARMER.

LOCK.

APPLIOATION FILED DB0. 1a, 190s.

Patented June 7, 1910.

2 SHEETS-SHEET 1.

UWE/WUR MORT/MER FARMER W/TNESSES d/WM@ ATTORNEYS;

M. H. FARMER.

LOCK.

APPLICATION FILED 1920.18, 1908.

2 SHEETS-SHEET 2.

Patented June 7, 1910.

MORT/MER HF HRA/1ER v ma mm l g U TTOH/VEVS MORTIMER HOWARD`FARMER, OF VIRDEN, ILLINOIS.

LOCK.

Specication of Letters Patent. Patented June 7, 1910.

Application filed December 18, 1908. Serial No. 468,101.

To all 'whom 'it may concern:

Be it. known that I, Mon'rinnn HowAnD FARMER, a citizen ot' the United States, and a resident of Virden, in the county'of Macoupin and Statey of Illinois, have made certain new and useful Improvements in Locks, of which the following is a specification.

M v invention relates to improvements in spring locks and it consists in the combinaf tions, constructions and .nrangcments here.- in described and claimed.

An object of my invention is to provide a simple form of locking mechanism which may act in the manner of an ordinary spring lock until the door or other swinging member to which is is applied is shut, when the lock will immediately become dead and will require a key to unlock it.

A further object of my invention is to provide novel means for rendering the latch bolt immovable against the application of instruments, such as a chisel or other device, which will be sufficient to force the latch bolt'of an ordinary spring lock back with ease.

Other objects and advantages will appear in the following specification and the novel features of the invention will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings, in which- Figure 1 is a plan view of the device showing the locking mechanism in its normal position, the upper plate being removed. Fig. 2 is a similar view showing the latch bolt in its retracted position. Fig. 3 is a longitudinal section through the device. Fig. 4 is a top View of the bot-tom plate. Fig. 5 is a section along the line 5 5 of Fig. 1. Fig. G is a section along the line 6-6 of Fig. 1. Fig. 7 is a perspective View of the key and the push cams. Fig. 8 is a perspective view of the guard plate.

Referring now particularly to Fig. 3 I have shown therein a metal casing consisting of a main portion A and a bottom portion B. The casing is divided by a transverse partition C having a slot c. Project-ing through the vforward part of the casing is the latch bolt D. This is provided with the longitudinal dove-tailed slot d, as clearly shown in Fig. 6. Secured to the rear end of the latch bolt is a guide rod E, about which is coiled a spiral spring F. The guide rod E extends through an opening in the partition C and is rigidly secured to the central portion of a U-shaped member G, the latter being for the purpose of operating the latch bolt and limiting its movement in either direction.

The guard plate H is shown in Fig. 8. It is preferably made of a single piece of metal stamped in the form shown and is provided with a rectangular slot It, an upturned flange h at its end and a smaller upturned flange between the slot. l1. and the flange L. The oppositely inclined flanges las are arranged to enter the slot (l of the latch bolt D, as clearly shown in F ig. (i.

In Fig. 7 I have shown the push cams for operating the latch bolt after the door shut. These push cams consist of a pair of members J and K, each provided with the curved arms j and c, respectively. In the ligure I have shown the members J and K as being permanently secured to a spindle L. The push cam K is provided witha laterally projecting wing lf* having a central curved portion cy. The spindle L projects through a key hole in the casing A and push cams J and K are arranged respectively above and below the U-shaped'inember G. The arms and are bent inwardly to engage the enlarged ends g and g of the meinber G. ,f

Pivotally supported on the partition C is a latch plate P whose end extends underneath the curved portion lay of the cam member K in the normal position of tbc latter. The end p of the plate I is turned outwardly 'so as to be engaged by the cam Wings z'4 of the push cam K. The opposite end of the latch plate is provided with an inwardly projecting stop p2, which is arranged to engage the rear end. of the guard plate H, as shown in the drawings.

The removable plate B is provided with a spring S which normally keepsthe guard plate H in its forward position by the eugagement of the flange h2. The leaf spring R, attached to the plate B, bears upon the latch plate P to hold the latter normally in line with the latchA bolt D. The pins T serve the purpose of guide members for the latch plate P when the parts are assembled;

From the foregoing description of the variousy parts of the device the operation thereof may be readily understood. When the parts and B are in their assembled position, the guard plat-e H is forced to the of the spiral spring F.

front as shown in Fig. v1, but both the plate H and the latch bolt D may be forced inwardly, the former against the tension of its spring S and the latter against the tension Thus, when the latch bolt comes into contact with the strike plate on the door frame, both of these members are forced inwardly. It will be observed that in the normal position of the Iguard plate H its rear end l engages thecurved cam surface p3 of the latch plate P, thereby forcing the latter into the position shown in dotted lines in F ig- 3, in which it will be secu that the. stop 712 is out of the way of the latch bolt D, thereby permitting the latter to be forced inwardly. When the door is closed, however, the latch. bolt springs backinto position, thereby locking the door While the plate H remains in its shifted position, being held there by one side of the strike plate which presses against the flange h', see Fig. 3. This forces the latch plate into the position shown in Fig. 2. Just as soon as the rear end 71,5 of the guard plate leaves the cam portion p3, the latch plate Pis forced inwardly by means of the spring R, the stop p2 entering the slot L of the guard plate H and taking the position immediately behind the latch bolt D, as shown in Fig. 3. The lock is now dead and cannot be opened except by means of the spindle L. When the spindle L is turned the cam wings la* first engage the outwardly turned end p of the latch plate'P, thereby forcing the latter inwardly when the stop .p2 will be thrown out of engagement with the latch bolt D. On further movement of the key one of the arms lo and y' will come into contact with the arms of the member G, thereby forcing the latter to the rear and drawing with it the latch bolt and the guard plate H. The position of the mechanism when the door is being unlocked is shown in Fig. 2. After the door is opened the key releases the guard plate H and the latch bolt D assumes the position shown in Fig. l.

I am aware that devices have been made in which the dead locking of the bolt has beenaccomplished and I do not claim broadly such a device, but

What I claim isl. The combination with a strike plate provided with an opening, of a spring actuated latch bolt, a slotted guard plate slidably mounted on said latch bolt,V a spring actuated latch plate having a stop adapted to project through thel slot in said guard plate into the path of the latch bolt.

2. The combination with a strike plate provided with an opening, of a spring actuated latch bolt, a slotted guard plate slidably mounted on said latch bolt, a springactuated latch plate provided with a cam adapted to engage said guard plate, a stop on said latch plate adapted to project through the slot in said guard plate, said stop being held normally out of the path of said latch bolt by the engagement of the guard platewith the cam on the latch plate and permitted to spring into the path of the bolt through a movement of said guard plate.I

3. A lock comprising a easing, a springyactuated latch bolt adapted to reciprocate in said casing and provided with a slot, a slotted guard plate arranged to reciprocate in the slot in said bolt, a pivoted stop having a caln portion normally in engagement with the rear end of said guard plate but adapted to'enter within the slot in said guard pla'te when the latter is moved, thereby bringing said stop'into the path of the latch bolt, a cam member having a central curved portion and laterally extending cam wings arranged to engage the rear end of said pivoted stop to raise the latter out of engagement with said latch bolt, integral curved arms carried by said cam member, a U- shaped sliding plate attached to said bolt, and a spindle adapted to enter a slot in said cam member to4 force said arms into enga e* ment with said U-shaped sliding piece or retraeting the bolt. y

, MORTIMER HOWARD FARMER. Witnesses:

HERMONE R. GoE'rTE, JOSEPH W. EVERTS. 

